Jeff,

“There are hot water coils designed to fit inside traditional free-standing woodstoves, and hydronic water jackets designed to fit inside a conventional masonry fireplace”

Brad

Brad,

I have answered this question before.

Stricter Federal government regulations and easy lawsuits against manufacturers have driven all the manufacturers of this type equipment out of the US market.

Back in the 70′s and 80′s there were many manufacturers of wood-fired hot water heaters, hydronic fireplaces, and hot water coil inserts for wood stoves.  Some moved to Mexico and are selling lots of these products in Mexico and others just went out of business.

There may be one or two left, but about the only water heating wood stoves made now are the outdoor wood-fired boilers you see advertised in this magazine that pipe the hot water into the house.

Hope this helps,

Jeff Yago

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Jeff

I am looking at replacing a traditional fireplace with a wood stove insert that can be used in a hydronic floor system.

I looked over your article on the fireplace you installed in your home and have spoke to and web searched for wood stoves that circulate water for heated floors and find only the “long burners” for outside or commercial “furnaces”, nothing that would be appropriate for a great room/ranch application.  Can you point me toward manufacturers that have this type of product?

Thank you.

Mark J. Bechtel

Mark,

Jeff Yago

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Jeff,

Corrie

Corrie,

I have an electric fan device that sits on top of our wood stove and the unit generates electricity from the heat to run the small fan.  Unfortunately, you get only a very tiny amount of electricity from this solid state thermal energy conversion process, and all the electrical equipment must be able to withstand the high temperatures.   Yes, you could get enough electricity from wood stove to do this, but the cost and size of the equipment to do it would be un-realistic.   Your best bet is to spend your money on solar modules.

Good luck,

Jeff Yago

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Jeff,

Jim:

Sounds like you have a real classic and built to last. Unless you are required in your area to add this, I would not waste my time on this stove. If you decide to do anything, the easiest will be one of the kits that fit into the flue on top of the stove.

Good Luck,

Jeff Yago

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Dog bless the EPA. They have made my new wood stove so clean-burning that it just doesn’t act right. It seems to me that I’m using more wood than needed. If I fill it with wood and close the air control, it burns at the same high rate as with the control open.

Don:

I know what you mean. A generator manufacturer we have represented for many years made a really great residential size home backup generator with a 1800 RPM cast iron engine. This low RPM unit would last forever, but in the mid 90′s, new EPA regulations were implemented that this low speed engine could not meet so they stopped making them altogether and now you must buy a larger model with a 3600 RPM engine that meets the new EPA regulations but does not live long due to the higher RPM and light weight engine. Also, the larger model uses more fuel than the smaller unit that was killed off.

During one winter under Jimmy Carter, he mandated that all Federal buildings had to set their thermostats down to 68 degrees due to the energy crisis. I was involved in facility engineering at that time and almost all large office buildings could easily stay above 73 degrees in the winter just from the heat of people and lights without using any heating. In order to meet this presidential dictate, we had to run the air conditioners in many of these buildings to “lower” the space temperature since most high rise buildings no longer have windows you could open and these large internal heat gains could only be reduced using the air conditioners! Just another mindless regulation made by people who do not realize all the unintended results of their decisions.

As to wood stoves, it depends on the type you have. All new EPA approved wood stoves have either a catalytic insert near the flue outlet or require baffles to pass the intake combustion air around the fire box to preheat the air first. It sounds like you have the baffle type as the combustion air intake is usually a “grille” or series of vent holes under the stove bottom, not the old style “damper” you could open and close off. I do not know how your stove is designed, but your air control may be more cosmetic than functional, and most of the combustion air may be entering at the bottom or rear through a much larger opening.

A final note, many newer stoves do not require the large flues that older stoves needed to get a good draft, and if your flue is too large, it may be causing the stove to “suck” air around any draft closure you are trying to damper the fire. I would put this back on the sales outlet where you purchased the stove for their input.

Good luck,

Jeff Yago

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Hi Jeff,

Mike:

Although most heating of buildings and homes before the advent of central air conditioning systems was hot water or steam radiators. Now things are changing again and many up-scale homes are starting to utilize hydronic heating due to the higher energy savings and comfort. Our 3 story solar home has a built-in masonry fireplace in our ground level (partly below grade) family room. This fireplace has a Hydro-Heater hydronic firebox which is “hollow” on all 3 sides and the bottom which allows water to flow around these areas then this water flows up into a heat exchanger containing 90 feet of boiler tubing. This heated water is then pumped into a air heat exchanger located in the discharge side of my central air handling unit, which circulates this heated air to every room of our home including all 3 floors. When we have a roaring fire in this fireplace, every room of our home stays at the same temperature and there are no cold spots.

I have also designed many systems like this for others only we piped the heated water to baseboard hot water radiation located in each room, and used motorized zone valves to allow each room wall thermostat to separately control the temperature of each room. Although most of the wood-forced boilers you will find advertised these days usually are the self-contained type that is located outside and piped into the home, there are still several manufacturers that offer “hydronic inserts” that look like a log holder that you place inside a standard fireplace. Many wood stove manufacturers offer an optional hot water coil feature, but these are usually intended to only heat a domestic hot water tank and not the entire house.

Yes, you can heat a radiant floor, but the problem is most radiant floor heating systems keep the water temperature in the lower 100 to 120 degree range, and most hydronic wood stoves can easily produce hot water in the higher 160 to 180 degree range which is much better suited for a baseboard radiation system. This means a radiant floor system will require a storage tank with one small pump circulating tank water through the hydronic fireplace to heat the tank, and a second small pump to circulate heated tank water at a different flow rate through the radiant floor piping. Remember, boiler water or water passing through hot water radiators and radiant floor piping usually will include additives to reduce sludge and rust, and you cannot mix with your domestic hot water system (sinks and baths), so if you want to also heat your domestic hot water tank, you will need a separate coil in this storage tank for that piping.

You are on the right track, but remember, these are classified as a “boiler” and if you don’t include the proper pressure and temperature safety relief valves in your piping, these things can blow up and do some real damage. Also, manufactured hydronic stoves are made from “boiler grade” steel which is much stronger with no flaws or weak spots. This may be why there are not as many manufacturers these days and why I do not agree with your “beer keg” idea!

Good luck,

Jeff Yago

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Some 30 years ago I help install an hydronic system in a house in northeast Texas that used a similar system but went a lot farther: We ran hi-temp PVC thru the slab and out into a coil (radiator) in a 10,000 gallon water tank. Then we hooked it up with black pipe to the fireplace by embedding it into the hi-temp (stove) cement. Added a pop off valve at a low pressure (approx 110 psi) and a pump for backup.

Keven:

As I mentioned in the article, we designed several systems that used a storage tank. Tank water was heated from the hydronic wood stove which was then circulated later at night to circulate to the home’s floor slab after the fire was out. Most of these tanks were under 1000 gallons since they would be located in the garage, and they took about 4 hours of a really big fire to heat up. If you had a 10,000 gallon tank, it must have taken days to get the water hot, but then you would be able to heat for days without a fire once it was!

We used standard 3/4″ copper which come in 60 foot rolls for our heat exchanger and placed two coils in the tank which kept the water that circulated through the stove and coils from mixing with the water that stayed in the tank. All of our systems required two pumps and three automatic zone valves to re-direct the flows since you need three separate operating modes: stove to tank, stove to house, and tank to house. If you were able to do all this without any pumps or valves, you must have had a really good thermo-syphen effect with your hydronic stove.

Thanks for the description of your very large system.

Jeff Yago

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